CN2475146Y

CN2475146Y - Fuel cell with high output power

Info

Publication number: CN2475146Y
Application number: CN01238846U
Authority: CN
Inventors: 胡里清
Original assignee: Shanghai Shen Li High Tech Co Ltd
Current assignee: Shanghai Shenli Technology Co Ltd
Priority date: 2001-04-13
Filing date: 2001-04-13
Publication date: 2002-01-30
Anticipated expiration: 2011-04-13

Abstract

The utility model relates to a fuel battery which is provided with higher output power, comprises a film electrode which is composes of at least two parallel connection individual plates, a diversion plate, a front end plate, a back end plate, a pulling rod, a cooling unit and a monitoring unit. A single battery is formed by two diversion plates clamping a film electrode between. A plurality of single battery is serially connected to form a fuel battery. Compared with the existing technology, the effective area of the utility model film electrode is increased doubly, thus the power can be improved doubly. Meanwhile, the gas and oxidant gas are distributed uniformly and the battery runs steadily.

Description

Fuel cell with higher output power

The present invention relates to batteries, and more particularly to electrochemical fuel cells.

An electrochemical fuel cell is a device that is capable of converting hydrogen fuel and an oxidant into electrical energy and reaction products. The inner core component of the device is a Membrane Electrode (MEA), which is composed of a proton exchange Membrane and two porous conductive materials sandwiched between two surfaces of the Membrane, such as carbon paper. The membrane contains a uniform and finely dispersed catalyst, such as a platinum metal catalyst, for initiating an electrochemical reaction at the interface between the membrane and the carbon paper. The electrons generated in the electrochemical reaction process can be led out by conductive objects at two sides of the membrane electrode through an external circuit to form a current loop.

At the anode end of the membrane electrode, fuel can permeate through a porous diffusion material (carbon paper) and undergo electrochemical reaction on the surface of a catalyst to lose electrons to form positive ions, and the positive ions can pass through a proton exchange membrane through migration to reach the cathode end at the other end of the membrane electrode. At the cathode end of the membrane electrode, a gas containing an oxidant (e.g., oxygen), such as air, forms negative ions by permeating through a porous diffusion material (carbon paper) and electrochemically reacting on the surface of the catalyst to give electrons. The anions formed at the cathode end react with the positive ions transferred from the anode end to form reaction products.

In a pem fuel cell using hydrogen as the fuel and oxygen-containing air as the oxidant (or pure oxygen as the oxidant), the catalytic electrochemical reaction of the fuel hydrogen in the anode region produces hydrogen cations (or protons). The proton exchange membrane assists the migration of positive hydrogen ions from the anode region to the cathode region. In addition, the proton exchange membrane separates the hydrogen-containing fuel gas stream from the oxygen-containing gas stream so that they do not mix with each other to cause explosive reactions.

In the cathode region, oxygen gains electrons on the catalyst surface, forming negative ions, which react with the hydrogen positive ions transported from the anode region to produce water as a reaction product. In a proton exchange membrane fuel cell using hydrogen, air (oxygen), the anode reaction and the cathode reaction can be expressed by the following equations:

and (3) anode reaction:

and (3) cathode reaction:

in a typical pem fuel cell, a Membrane Electrode (MEA) is generally placed between two conductive plates, and the surface of each conductive plate in contact with the MEA is die-cast, stamped, or mechanically milled to form at least one or more channels. The conductive plates can be plates made of metal materials or plates made of graphite materials. The flow guide pore canals and the flow guide grooves on the conductive polar plates respectively guide the fuel and the oxidant into the anode area and the cathode area on two sides of the membrane electrode. In the structure of a single proton exchange membrane fuel cell, only one membrane electrode is present, and a guide plate of anode fuel and a guide plate of cathode oxidant are respectively arranged on two sides of the membrane electrode. The guide plates are used as current collector plates and mechanical supports at two sides of the membrane electrode, and the guide grooves on the guide plates are also used as channels for fuel and oxidant to enter the surfaces of the anode and the cathode and as channels for taking away water generated in the operation process of the fuel cell.

In order to increase the total power of the whole proton exchange membrane fuel cell, two or more single cells can be connected in series to form a battery pack in a straight-stacked manner or connected in a flat-laid manner to form a battery pack. In the direct-stacking and serial-type battery pack, two surfaces of one polar plate can be provided with flow guide grooves, wherein one surface can be used as an anode flow guide surface of one membrane electrode, and the other surface can be used as a cathode flow guide surface of another adjacent membrane electrode, and the polar plate is called a bipolar plate. A series of cells are connected together in a manner to form a battery pack. The battery pack is generally fastened together into one body by a front end plate, a rear end plate and a tie rod.

A typical battery pack generally includes: (1) the fuel (such as hydrogen, methanol or hydrogen-rich gas obtained by reforming methanol, natural gas and gasoline) and the oxidant (mainly oxygen or air) are uniformly distributed in the diversion trenches of the anode surface and the cathode surface; (2) the inlet and outlet and the flow guide channel of cooling fluid (such as water) uniformly distribute the cooling fluid into the cooling channels in each battery pack, absorb heat generated by electrochemical exothermic reaction of hydrogen and oxygen in the fuel cell and carry the heat out of the battery pack for heat dissipation: (3) the outlets of the fuel gas and the oxidant gas and the corresponding flow guide channels can carry out liquid and vapor water generated in the fuel cell when the fuel gas and the oxidant gas are discharged. Typically, all fuel, oxidant, and cooling fluid inlets and outlets are provided in one or both end plates of the fuel cell stack.

The positive hydrogen ions in the anode region migrate through the proton exchange membrane and usually need to carry a large number of water molecules to pass through together, so that the water molecules must be kept on the two side surfaces of the membrane to ensure that the migration conductance of the positive hydrogen ions is not affected. Therefore, the fuel and oxidant gases must be humidified before they enter the active region of the fuel cell to react in order to ensure that the membrane in the membrane electrode is saturated with water.

The overall design of a pem fuel cell varies greatly depending on the intended use of the cell. At present, the proton exchange membrane fuel cell used as a high-power movable power supply is designed, and the following measures are mainly adopted to improve the power density.

(1) Increasing the effective area of the membrane electrode to increase the output current;

(2) the thickness of the flow guide polar plate is reduced, the weight of the whole battery pack is reduced, and the volume is reduced;

(3) the fuel gas for intensifying the operation and the oxidant are operated under the conditions of pressure, concentration, temperature and the like so as to output larger power.

The first method for increasing the output power of the battery pack often has great limitations, mainly because the fuel gas and the oxidant gas are difficult to be uniformly distributed along with the increase of the area to a certain degree, and the electrochemical reaction speeds of all parts of the effective area are different, so that the current density is different, and the rate of the product water generated by all parts is different, thereby increasing the difficulty of water, heat management and control of the fuel cell with large area, often causing the local overhigh temperature, increasing the risk of pore burning of the membrane electrode, or causing the local low power generation efficiency and the expected power to be far different.

The second method for increasing the output power density of the battery pack has a great limitation because the guide plate is thin to a certain extent, and thus, the guide plate is liable to have insufficientmechanical strength, and if a graphite material is used, the guide plate is liable to cause a risk of leakage of fuel gas and oxidant gas, and is liable to be broken.

The third method has great limitations to increase the output power of the battery pack, such as increasing the operating air pressure of the fuel cell, increasing the power consumption of the air compressor of the peripheral auxiliary system, and increasing the volume and weight of the air compressor.

The present invention aims to overcome the defects of the prior art and provide a fuel cell with high output power, which can improve the power by times and operate stably.

The purpose of the utility model can be realized through the following technical scheme: a fuel cell with high output power is prepared as connecting film electrode with at least two independent pole plates in parallel, connecting said guide plate to front end plate and back end plate in parallel, connecting said front end plate and back end plate to form a fuel cell in series, cooling heat generated in said process by cooling unit and monitoring data in said process by monitoring unit The corresponding position of the flow guide polar plate is provided with a common air inlet channel and a common air outlet channel.

The membrane electrode is formed by connecting two independent pole pieces in parallel.

The flow guide polar plate is formed by connecting two independent polar plates in parallel.

The membrane electrode is integrally formed.

The flow guide polar plate is integrally formed.

The effective area of the membrane electrode is 200-400 cm²×2。

The area of the flow guidepolar plate is 20cm multiplied by 2.

The catalyst is a metal platinum catalyst.

The utility model discloses owing to adopted above technical scheme, the effective area of its membrane electrode can increase at double, therefore its power has also obtained the improvement at double, and simultaneously, fuel gas, oxidant gas distribution are even, and each part electrochemical reaction speed of membrane electrode effective area is the same, and the current density of membrane electrode is even, and the battery operation is stable. At present, for large and medium fuel cell stacks with power of 5 to 10 kilowatts or more than 10 kilowatts, the effective area of the membrane electrode of a single cell is about 200 to 400cm²The area of the flow guide polar plate is about 20cm multiplied by 20cm, if the flow guide polar plate and the module electrode are designed in parallel, the power can be doubled or multiplied, and the battery pack can achieve the same maturity and stability in operation. If the guide plate and the die electrode are respectively designed into a whole, the power density of the fuel cell set is much higher than that of two fuel cell sets which are put together and run in parallel. Furthermore, the utility model discloses still with fuel hydrogen, oxidant air, the import and the exit channel of cooling fluid (deionized water) jointly admit air jointly and exhaust jointly, thereby make the utility model discloses fuel cell compact structure still can reduce product cost.

Fig. 1 is a schematic view of an appearance structure according to an embodiment of the present invention;

fig. 2 is a front view of a membrane electrode according to an embodiment of the present invention;

fig. 3 is a front view of a guide plate according to an embodiment ofthe present invention;

fig. 4 is a schematic structural view of a flow guide channel according to an embodiment of the present invention.

The present invention will be further described with reference to the accompanying drawings and specific embodiments.

As shown in the figure, for the embodiment of the fuel cell with higher power of the present invention, it includes a membrane electrode 1 that can conduct proton and is formed by connecting two independent pole pieces in parallel and integrally forming, a flow guiding pole plate 2 that is formed by connecting two independent pole pieces in parallel and integrally forming, and a cooling water clampThe plate 3, the front end plate 4, the rear end plate 5, the pull rod 6 and the auxiliary monitoring device; catalyst 7 is adhered to two sides of the membrane electrode 1, porous carbon paper 8 is arranged on the outer side of the catalyst, the flow guide polar plates 2 are provided with flow guide grooves 9 which can respectively guide fuel and oxidant, the membrane electrode 1 is clamped by the two flow guide polar plates 2 to form a single cell, and a plurality of single cellsThe cells are connected in series, a cooling water clamping plate 3 is arranged between each single cell, a front end plate 4 and a rear end plate 5 are arranged in front and at the back respectively, and the front end plate and the rear end plate are fastened together by a pull rod 6 to form the fuel cell. The corresponding positions of the front end plate, the rear end plate, each membrane electrode and each flow guide polar plate of the fuel cell are respectively provided with a common fuel inlet channel 10J for feeding fuel, oxidant and cooling water, a common oxidant inlet channel 11J, a common cooling water inlet channel 12J, a common fuel outlet channel 10C for feeding fuel, oxidant and cooling water, acommon oxidant outlet channel 11C and a common cooling water outlet channel 12C. The effective area of the single cell membrane electrode of the present example was 600cm²The area of the flow guide polar plate is 800cm²The power of the fuel cell is 20 kilowatts, which is doubled compared with the power of the existing single-pole plate direct-stacked cell.

Of course, if constitute membrane electrode with three, four or even more multi-disc single membrane electrode slices parallelly connected and integrated into one piece, constitute the water conservancy diversion polar plate with three, four or even more multi-block unipolar board parallelly connected and integrated into one piece simultaneously, then the utility model discloses the power of battery will improve triple, quadruple or even more multiple times than current unipolar board directly fold formula battery.

Claims

1. A fuel cell with high output power comprises a membrane electrode capable of conducting proton, a guide polar plate capable of respectively leading in fuel and oxidant, a front end plate, a rear end plate, a pull rod, a cooling unit and a monitoring unit, wherein catalyst and porous carbon paper are attached to two sides of the membrane electrode, the guide polar plate is provided with a guide groove, a membrane electrode is clamped by the two guide polar plates to form a single cell, the front end plate and the rear end plate clamp a plurality of single cells and are connected in series through the pull rod to form the fuel cell, the cooling unit cools heat generated in the process, and the monitoring unit monitors process data The rear end plate, the membrane electrodes and the flow guide polar plate are provided with a common air inlet channel and a common air outlet channel at corresponding positions.

2. The fuel cell with higher output power of claim 1, wherein the membrane electrode is formed by connecting two single pole pieces in parallel.

3. The fuel cell of claim 1, wherein the current-guiding plate is formed by connecting two separate plates in parallel.

4. The fuel cell of claim 2, wherein the membrane electrode is integrally formed in one piece.

5. The fuel cell of claim 3, wherein the flow guide plate is integrally formed as a single piece.

6. The fuel cell with high output power of claim 4, wherein the effective area of the membrane electrode is 200-400 cm²×2。

7. The fuel cell of claim 5, wherein the area of the current-guiding plate is 20cm x 2.

8. The fuel cell with higher output power according to claim 1, wherein the catalyst is a platinum catalyst.